1. Field of the Invention
This invention pertains to the use of beams of laser light to measure the position, direction or velocity of a circular rotating device (such as a shaft) or of a linear motion device (such as an x, y table). The laser beams reflect off the encoded surface of a specially prepared disk or strip (similar to the commonly used "pits" and "lands" used to encode audio, computer data, or video information) for the purpose of very high accuracy measurement of the position, velocity, and direction of a rotating or linear motion device to which the disk or strip is attached.
2. Description of the Background Art
There are a variety of devices that have been, and which are currently used, for measuring the rotational position and direction of a rotating body, or the position and direction of a linear device such as an x, y table. These include, without limitation, potentiometers, optical encoders based upon radial lines scribed on a disk, optical encoders based upon bar code technology, encoders based upon on a magnetic disk, and other devices. Most of these devices are of limited resolution or have other limitations such as very high cost or large size.
Presently, there are no devices that provide a high degree of accuracy, at a low cost, in a reasonably sized package. This invention satisfies the need for high resolution and low cost without sacrificing accuracy.